A word that represents a noun in any sentence is known to be a Pronoun. It not only represents a noun but anything that functions as a noun. We need pronouns in our language to avoid the repetition of nouns. For example,
-For single word noun: Phani ate an Apple. He threw the seeds.
-For mutli-word noun: Sita bought Raw Silk Saree, it was very expensive.
-For noun clause: The Glaciers in the south have started to melt. It is because of the increasing global warming.